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• Monitoring Plan <br />The first blasting of overburden will take place west of the <br />Engleville Gulch drainage near the point where the coal outcrops <br />in the drainage. This location is approximately 500 feet from the <br />gas pipeline. Vibra-Tech Engineers, Inc. with local offices in <br />Westminster, Colorado has been contracted to provide initial <br />monitoring assistance and ongoing rental of seismic equipment. It <br />is planned that the initial blast will be monitored by 5 <br />seismographs placed at various distances from the blast in order <br />to gather data points at various scaled distances to build the <br />site specific particle velocity vs. scaled distance relationship. <br />An example of this relationship is given in Figure 1. <br />The seismograph to be used is a brand new model from Vibra-Tech <br />called the Everlert II. Its specifications are enclosed in this <br />section. The advantages of this instrument are a) it can <br />accurately record ground vibrations from .O1 in/sec up to 8.0 <br />in/sec. and b) it stores all data on a 1.44 mb floppy disk for <br />permanent storage. <br />From the initial blast, 5 data points will be available to <br />determine the site specific relationship as shown in Figure 1. <br />This will be done on site immediately after the blast. An <br />• approximate 958 line will be determined and the scaled distance <br />will be evaluated at a peak particle velocity of 6.5 in/sec. The <br />958 confidence line is defined as that line where no more than 58 <br />of the data points lie above. If this scaled distance results in <br />an explosive weight over 45.6 pounds at a distance of 50 feet, <br />the weight of explosive will be adjusted accordingly. <br />Essentially, the square root scaled distance at the 6.5 in/sec <br />particle velocity from the plot will determine how much explosive <br />weight can be detonated at any distance from the gas line. <br />Monitoring will continue during the mining operation as follows: <br />For blasting from 250 to 500 feet from the gas line - 1 out of <br />shots will be monitored unless 4 consecutive monitored shots <br />result in a peak particle velocity of less than 3.0 inches per <br />second measured at the gas line. If this occurs, no additional <br />monitoring will take place at these distances. The pounds of <br />explosive per delay will not be increased from the monitored <br />shots. <br />For blasting from 100 to 250 feet from the gas line - 1 out of 3 <br />5 <br />